1. Field of the Invention
The present invention relates to an MPEG decoder which receives a data stream including MPEG-coded data which contains closed caption (CC) data in a user data area as character codes or in a picture data area as NRZ-converted pixel data and outputs at least an MPEG-decoded video data stream including the CC data such that a TV set with a text decoder can display the CC and its application to an optical disc player such a video-compact disc (video-CD) player, a digital video disc (DVD) player, etc.
2. Description of the Prior Art
A technique is well known for Inserting closed caption data in an undisplayed part of the video signal and for decoding the data into a text and superimposing the text over the displayed image. Specifically, in a system in which horizontal scanning lines H1 through H21 (H264 through H284) of all the horizontal scanning lines H1 through H525 are used as vertical blanking periods and H22 through H263 (H285 through H525) are used as video signals, the broadcast station inserts text codes as NRZ (non-return-to-zero)-modulated signals in one of the vertical blanking periods, e.g.. H21, and the TV receiver converts the NRZ-modulated signals into a text image by using an text decoder and superimposes the text image over the video image.
Similarly, there may be cases in which text information (closed caption data) is included in MPEG coded data to be transmitted or recorded on an optical disc (video-CD, DVD, etc.) in a transmission or recording of moving pictures, respectively. In such cases, a receiver or an optical disc player can insert the text information cointained in the MPEG coded data received from the transmission path or reproduced from the optical disc into the line H21 of a video signal obtained by MPEG decoding the MPEG coded data and output the video signal to the TV receiver. However, if this is to be done during the complicated process of MPEG data stream comprising I, P and B pictures, it will make the whole process more complicated.